I tried Shelter on /e/ and it seems to work great (although I don’t fully understand how it works*), only it doesn’t seem to agree with the bliss launcher.
Sheltered apps don’t appear on the launcher anymore and can only be launched through shelter - which makes sense, but after some time more apps that are not sheltered start to disappear and after a reboot suddenly only sheltered apps are shown.
You can then basically only launch those apps if you happen to get a notification from them.
So my tip: If you want to use shelter install a different launcher first.
Also: If you don’t want your sheltered apps to communicate with G%§$e disable device registration, cloud messaging & safetynet in the shelter’s microg settings (microg is automatically cloned to the shelter and the settings will be set to default even if you changed them before).
*Btw, does anybody know where I can find an extended guide on how shelter works? The readme e.g. doesn’t say whether sheltered apps can access eachother’s data. If so I guess one shouldn’t shelter too many apps or you’ll risk leaking lots of data again.